A method is known, from Great Britain Patent No. GB 2,366,664. In that document, the fuel injection device has an injection valve that is outfitted with a piezoelectric element. By an appropriate activation, the injection valve may be brought into an open and a closed state. A prespecified electrical voltage has to be applied to the piezoelectric element in order to bring the injection valve into the open state. In this open state, an injection orifice is unblocked by a nozzle needle, so that the fuel is injected, for instance, into a combustion chamber of an internal combustion engine.
To determine the mass of the injected fuel, it is necessary to ascertain the point in time of the opening of the injection valve.
It is an object of the present invention to provide a method for operating a motor vehicle injection device, especially for a motor vehicle, using which, the point in time of the opening of the injection valve may be determined in a simple manner.